他对学习新语言非常热衷。

He is ___keen on learning new languages.

这把剪刀的刀片非常锋利，可以轻松剪开厚纸板。

The scissors have a ___keen blade that cuts through cardboard easily.

这位音乐家的听力非常敏锐，能分辨出最细微的音调变化。

The musician's ___keen hearing could detect the subtlest changes in pitch.

她对这份工作表现出了强烈的渴望。

She showed a ___keen desire for this job.